Involvement of outer membrane protein TolC, a possible member of the mar-sox regulon, in maintenance and improvement of organic solvent tolerance of Escherichia coli K-12.
Escherichia coli mutants with improved organic solvent tolerance levels showed high levels of outer membrane protein TolC and inner membrane protein AcrA. The TolC level was regulated positively by MarA, Rob, or SoxS. A possible mar-rob-sox box sequence was found upstream of the tolC gene. These findings suggest that tolC is a member of the mar-sox regulon responsive to stress conditions. When a defective tolC gene was transferred to n-hexane- or cyclohexane-tolerant strains by P1 transduction, the organic solvent tolerance level was lowered dramatically to the decane-tolerant and nonane-sensitive level. The tolerance level was restored by transformation of the transductants with a wild-type tolC gene. Therefore, it is evident that TolC is essential for E. coli to maintain organic solvent tolerance.
Aono
R
R
Department of Bioengineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan. raono@bio.titech.ac.jp
Tsukagoshi
N
N
Yamamoto
M
M
D000473:Alkanes / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001692:Biological Transport; D003510:Cyclohexanes / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006586:Hexanes / Q000494:pharmacology; D006838:Hydrocarbons / Q000494:pharmacology*; D026901:Membrane Transport Proteins; D008826:Microbial Sensitivity Tests; D009154:Mutation; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics; D012997:Solvents / Q000494:pharmacology; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics; D014161:Transduction, Genetic
D000473:Alkanes; D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003510:Cyclohexanes; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D006586:Hexanes; D006838:Hydrocarbons; C080002:MarA protein, E coli; C080004:MarR protein, E coli; D026901:Membrane Transport Proteins; D012097:Repressor Proteins; C080267:Rob protein, E coli; D012997:Solvents; D015534:Trans-Activators; D014157:Transcription Factors; C073126:tolC protein, E coli; C070725:SoxS protein, E coli; C012867:decane